The dwell angle, or dwell time, that is, the ON, or closed period of a switch, serially connected with the primary of the ignition coil, should preferably be controlled as a function of speed so that, under low-speed conditions, current will not flow through the ignition coil for an excessively long period of time. Ignition systems with speed-dependent ON-time of a controlled switch, in series with the ignition coil, have previously been proposed--see German Disclosure Document DT-OS 22 44 781. This system, as described, has the disadvantage that the transducer which provides the trigger signals to control the switch in series with the ignition coil must be accurately constructed and must provide output pulses of essentially uniform ON/OFF ratio. Construction of angle transducers providing output signals accurately allocated to angular positions of the crankshaft of the engine is expensive.